Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Influence of heat treatments at 850, 900 and 950°C on the formation of sigma phase for UNS S32750 super duplex stainless steel.
Submission Author:
Ernandes Marcos Scopel , ES
Co-Authors:
Ernandes Marcos Scopel, André Gustavo de Sousa Galdino, Temístocles Luz, Warlen Alves Monfardini, RICARDO BOLDRINI, Raquel Skíbina Verbeno
Presenter: Ernandes Marcos Scopel
doi://10.26678/ABCM.COBEM2021.COB2021-1440
Abstract
Super duplex stainless steels (SDSS) are recognized because of their excellent mechanical properties and high corrosion resistance when compared to other steels. However, when these materials are subjected to temperatures from 400 to 1010 °C they can be affected with the presence of deleterious phases, such as chromium carbide. In many cases the presence of these phases can decrease some properties, especially corrosion resistance due to the protective layer deterioration. Therefore, this work aimed to analyze the sigma precipitation on UNS S32750 super duplex stainless steel after solubilization at 1125°C, aged at 850, 900 and 950°C for 10, 100 and 1000 min, quenched in water and also furnace cooled for samples aged at the three temperatures for 1000 min. Microhardness were measured to evaluate the influence of sigma phase precipitation. It was observed an increase of hardness with aging temperatures and aging times, with approximately 418 ± 4 HV0.5 for furnace cooled sample at 850°C for 1000 min. Yet, it is important to highlight that when investigating the precipitation of the sigma phase, a greater nucleation was observed at the interface of the austenite/ferrite phase, in the initial times of aging, the precipitation of the deleterious phases in finer grains contributed to the increase in hardness at 850 °C and with stabilization at 950 °C, because of the nucleation of larger grains, as a consequence of the increase in time and temperature of the treatment and also seen the intergranular precipitation in the ferritic stage of the sigma phase. These results collaborate to improve the understanding of sigma phase precipitation, in order to contribute to the choice of the appropriate parameters for the welding processes of the SDSS UNS S32750.
Keywords
Super-duplex Stainless Steel, Phase Transformation, aging, phase sigma
